In order to achieve low-powered high-performance electronics, the size of transistors forming the building block of very large scale integrated (VLSI) circuits are drastically decreasing. However, tool resolution and sensitivity continue to be major challenges in semiconductor device fault isolation and analysis. As transistors continue to scale down to 10 nm nodes and beyond, well-known optical microscopy techniques no longer work due to wavelength limitations. For instance, conventional failure analysis methods involve the use of Focused Ion Beam (FIB) deposited pads or Scanning Electron Microscope (SEM). However, minute charge currents from the FIB and SEM adversely affect measured results. The induced charge from the FIB and SEM can even break the ultra-thin transistor tunneling gate oxide layer. In addition to this, Passive Voltage Contrast (PVC) techniques lack the sensitivity to identify faulty vias and contacts.
Single-tip Scanning Probe Microscopy, such as Atomic Force Probing (AFP) and Atomic Force Microscopy (AFM), is a powerful tool for non-destructive determination of root causes of IC chip failure, including extension to the sub 10 nm node regimes. However, AFM effectiveness is severely limited by its single tip design. As a result, a range of fundamental phenomena that exist in thin film materials and devices are inaccessible. As just one example, the effects of dislocations and grain boundaries in thin films cannot be characterized, as the ability to perform trans-conductance (conduction between two tips) measurements at the nanoscale is a critical gap. Trans-conductance would enable a richer understanding of how electrons transport and interact with their surroundings by offering insight into the local density of states, tip-sample coupling, transport mechanisms, scattering phase shifts and inelastic free mean paths of electrons.
Multiple-tips SPMs have been proposed as a way of overcoming the inherent limitations of the single-tip SPM. However, there have been significant challenges to engineering a suitable multiple-tips SPM. Previous approaches to a multiple-tip SPM have relied on independent macroscopically-fabricated probes. These platforms are complex, difficult to actuate, and have limited scale-down. They are also prohibitively expensive to manufacture.
Accordingly, there is a continued need in the art for multiple-tips SPMs that are both cost-effective and easily manufactured and functionalized to the specific investigation for which they will be utilized. Also needed are efficient and cost-effective methods of manufacturing multiple integrated tip probes.